Iran said there will be no talks with the US following growing tensions. How did things get to this point?

Michael Collins, USA TODAY

WASHINGTON – Tensions between the U.S. and Iran accelerated sharply following the Trump administration’s accusations that Tehran was behind a weekend attack on oil facilities in Saudi Arabia.

The attack, which disrupted more than 5% of the world daily oil supply, reignited fears of a military confrontation in the Middle East and comes amid months of growing hostilities between the U.S. and Iran.

Iran's supreme leader Ayatollah Ali Khamenei announced on Tuesday that "there will be no talks with the U.S. at any level" — remarks apparently meant to end all speculation about a possible U.S.-Iran meeting between the two countries' presidents at the U.N. later this month.

Here’s a closer look at Saturday’s attacks and other recent events that inflamed hostilities in the Middle East:

Iran denies responsibility

Secretary of State Mike Pompeo blamed Iran but offered no specific proof that it was behind the drone strikes on the world's largest oil processing facility and a major oil field Saturday. The installations, operated by state-owned Saudi Aramco, produce more than half of the country's crude oil.

Iran has denied any involvement in the strikes, but Yemen's Iranian-backed Houthi rebels claimed responsibility. Saudi investigators said their initial findings suggest the weapons used "came from Iran” but did not speculate on where the weapons were launched.

The U.S. government released satellite images showing the extent of the destruction and suggested the assault originated in Iran or Iraq rather than Yemen, where Saudi Arabia is fighting the Houthi rebels.

President Donald Trump said Monday that it looks as if Iran was responsible – but he doesn't want war.

"Well, it’s looking that way,” Trump said when asked whether Iran is responsible for the missile and drone strikes. “As soon as we find out definitively, we'll let you know. But it does look that way."

Earlier Monday, Trump questioned Iran’s denials of involvement, referencing an incident earlier this summer when Iran shot down a U.S. drone by claiming it was in Iranian “airspace.”

“They stuck strongly to that story knowing that it was a very big lie,” Trump wrote on Twitter. “Now they say that they had nothing to do with the attack on Saudi Arabia. We’ll see?”

On Sunday, Trump suggested on Twitter that the U.S. is prepared to retaliate.

“There is reason to believe that we know the culprit, are locked and loaded depending on verification, but are waiting to hear from the Kingdom as to who they believe was the cause of this attack, and under what terms we would proceed!” he wrote.

More: Iran denies attacking Saudi oil sites but prepared for 'full-fledged war'

Iran and U.S. ‘spies’

The attacks on the Saudi oil facilities come less than two months after tensions between the U.S. and Iran escalated over Iran’s claim that it had arrested 17 spies recruited by the Central Intelligence Agency.

Iran’s semi-official Fars news agency claimed in July that 17 spies had been taken into custody and said some of them already had been sentenced to death. The arrests reportedly occurred over several months, and those taken into custody worked on “sensitive sites” in the country’s military and nuclear facilities, an Iranian intelligence official told a press conference in Iran.

Trump called Iran’s claim “totally false. Zero truth.” Pompeo, a former CIA director, also dismissed the report, saying Iran has a long history of lying.

More: Truth or lies? What we know about Iran's claim that it arrested 17 spies working for the CIA

Iran seizes tanker

Just days before Iran claimed it had arrested spies for the CIA, Iran's Revolutionary Guard seized a British-flagged tanker in the Strait of Hormuz, ratcheting up hostilities in the Middle East.

The Revolutionary Guard said its naval forces had seized the Stena Impero tanker July 19 for allegedly violating maritime rules and regulations in the Persian Gulf. A dramatic audio recording released days later provided the tense moments leading up to the raid, which included the Guard's forces rappelling from helicopters to the ship's deck.

Two weeks ago, Iran released seven of the tanker’s 23 crew members.

More: How to turn Iran’s tanker mischief against the Islamic Republic

Drone drama

The day before the British ship was seized, Trump announced that the USS Boxer destroyed an Iranian drone that came within 1,000 yards of the warship and ignored multiple calls to stand down.

Neither Trump nor the Pentagon spelled out how the Boxer destroyed the drone or provided any video or other evidence from the incident. Several U.S. officials said the ship used electronic jamming to bring it down rather than hitting it with a missile.

Iran, however, said that all of its drones in the Persian Gulf had safely returned to their bases and suggested the U.S. had destroyed its own drone by mistake.

Trump, however, insisted there is “no doubt" that a U.S. warship destroyed an Iranian drone.

President Donald Trump

More drone drama

The USS Boxer incident was not the first drone drama in the region this summer.

Iran's Revolutionary Guards shot down a U.S. surveillance drone in June, a bold strike that drew a stern warning from Trump and prompted top Pentagon officials to formulate military response options.

Iran said the drone was destroyed over its coast and said the incident sent a "clear message" that the Persian Gulf nation was ready to defend itself from what it views as Western aggression. The Pentagon, however, said the incident played out in international waters over the Strait of Hormuz.

Regardless, the U.S. prepared to make a retaliatory strike on Iran, but Trump canceled the attack at the last minute.

Trump said U.S. forces had been “cocked and loaded,” but that he called off the attack just 10 minutes before it was to take place after learning that 150 Iranians would die in the strike.

Other tensions

Tensions between the U.S. and Iran have been building for months after the Trump administration pulled out of a 2015 nuclear deal negotiated by President Barack Obama’s administration and other world powers.

Those tensions escalated in June, when two tankers reported they had been attacked about 25 miles off the southern coast of Iran.

The Front Altair, loaded with the flammable hydrocarbon mixture naphtha from the United Arab Emirates, radioed for help as it caught fire. A short time later, the Kokuka Courageous, loaded with methanol from Saudi Arabia and Qatar, also called for help.

The U.S. Navy's Fifth Fleet said it received two distress calls and sent the guided-missile destroyer USS Bainbridge to the scene.

No nation or group claimed responsibility, and Iran denied it was involved in the attack.

But Pompeo told reporters the attack was the work of Iran. Pompeo said the assessment was based in part on U.S. intelligence, the expertise needed for the operation and other recent incidents in the region, which the U.S. also has blamed on Iran.

Sanctions

With tensions mounting, the Trump administration announced July 19 it is imposing new sanctions on a senior member of the Iranian-backed militant group Hezbollah.

The administration also announced a $7 million reward for information leading to the capture of 25-year fugitive Salman Raouf Salman and described the actions as part of its "maximum pressure" campaign on Iran.

The administration announced its actions on the 25th anniversary of an attack Salman is accused of ordering on a Jewish center in Buenos Aires, Argentina. The attack killed 85 people and wounded hundreds of others.

Since then, the U.S. and other nations have accused Salman of plotting other attacks from a base in Lebanon. Officials believe he is still in the Middle East, but do not know exactly where.

Contributing: Associated Press, John Bacon, David Jackson, Kim Hjelmgaard

This article originally appeared on USA TODAY: How did tensions between the United States and Iran reach this point?